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  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>变量之 - var、let、const</title>
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<body>

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<script>
  var name = 'cuvee';
  let age = 30;
</script>
<script>
  var name = 'Matt';
  if (typeof age === undefined) {
    let age
  }
</script>
<script>
  // 形成块级作用域
  // 暂时性死区
  // 冗余声明报错
  // 全局声明不生效
  // for循环声明
  // 条件声明
</script>

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